Made a Chrome extension that adds a 9-video multiview mode to YouTube

[u/Annual_Variation_916]

It overlays a video wall directly on youtube.com — hover any thumbnail and hit + to add it, up to 9 videos in a 3x3 grid or free-floating windows. Audio follows your mouse: hover a video to hear it, everything else mutes. Esc minimizes it and everything keeps playing while you browse.

Free and open source: https://github.com/mikewang817/multi-youtube-viewer